Systemic Mastocytosis Imitating Eosinophilic Enterocolitis.

Eosinophilic gastrointestinal disorders produce gastrointestinal dysfunction as eosinophils accumulate throughout gastrointestinal tissues. The majority of eosinophilic gastrointestinal disorders are a diagnosis of exclusion, and a magnitude of differentials must be considered. A history of anaphylaxis raises the suspicion that systemic mastocytosis (SM) is the foremost differential to be considered. SM (hematological neoplasm) is characterized by the accumulation of clonal mast cells in systemic tissues that causes gastrointestinal manifestations. In these rare cases, serum tryptase and tissue staining for c-kit/CD117 (an immunohistochemical marker of mast cells) will clinch the diagnosis. Gastrointestinal manifestations of SM are expeditiously resolved with combined oral antihistamines.